Peristaltic pump



June 3, 1969 A. H. CLEMENS 3,447,478

PERISTALTIC PUMP Filed March 3, 1967 Sheet of 2 FIGURE 5.

INVENTOR ANTON HUBERT CLEMENS ATTORNEY June 3, 1969 A. H. CLEMENS 3,447,478

PERISTALTIC PUMP Filed March 3, 1967 Sheet 2 of2 FIGURE 4.

' INVENTOR ANTON HUBERT CLEMENS BY ATTORNEY United States Patent US. Cl. 103-149 7 Claims ABSTRACT OF THE DISCLOSURE A peristaltic-type pump having non-adjustable primary pumping rollers and adjustable secondary pumping rollers whereby the pump can have adjustable pumping capacity. In one form of apparatus the pump base member against which the pump tube is pressed by the pumping rollers is in the form of an arm which can be moved away from the rollers to reduce the compression on the pump tube when the pump is not being operated. The pump base member can also have a rippled surface which reduces sliding wear on the pump tube.

Background and objects of the invention Peristaltic type pumps are well known in the art. These pumps usually consist of a base having a generally cylindrical surface, a rotatable shaft located coaxially along the axis of said cylindrical surface, and several rollers supported by said shaft and positioned near the cylindrical surface. An elastically deformable tube hav ing an inlet and an outlet is positioned between the cylindrical surface and the rollers in such manner that the elastically deformable tube is deformably closed by the rollers wherever the rollers come in contact with the tube. As the shaft is rotated, the rollers move along the tube and create a peristaltic pumping action. The tube is anchored in at least one point along its length so as to prevent gross tube movement through the pump.

These prior art pumps had several disadvantages. First, they had a fixed constant volume capacity at a given pump speed. Second, there was undesirably high wear on the elastic tubes which necessitated frequent pump shut-downs for replacement of said tubes. Third, if the pump were shut down for any extended period with the shaft not rotating, the constant pressure of the rollers at fixed points on the tube tended to permanently deform the tube at these poins. This permanent deformation of the tube can cause non-uniform pump operation when the pump is again operated.

It is an object of the present invention to provide a peristaltic type pump having a variable pumping capacity.

It is another object of the present invention to provide a peristaltic pump which has reduced wear on the elastic tube thus reducing pump shut-downs due to tube failure.

It is a further object of the present invention to proprovide a peristaltic type pump which ha means for releasing roller pressure on the elastic tube when the pump is not operating.

Statement of the invention In accordance with the present invention, an improved peristaltic type pump is provided comprising a base, a plurality of primary rollers capable of being positioned adjacent to said base and in which position said primary rollers can compressively deform an elastically deformable tube positioned between said primary rollers and said base so as to close the central passage of said tube, a plurality of secondary rollers each positioned between two adjacent primary rollers, said secondary rollers being capable of being adjustably positioned adjacent and with respect to said base to afford selective compression Patented June 3, 1969 around and in radially spaced relation with respect to said shaft.

In another aspect of the invention, the base can be mounted for movement between an operative position wherein the tube is under compression between the cylindrical surface of said base and the rollers, and an inoperative position wherein the tube is not under such compression.

Description of drawings The invention will be described in further detail with respect to the accompanying figures wherein:

FIGURE 1 is a plan view of one form of peristaltic type pump of the present invention;

FIGURE 2 is a plan view with a partial cut-away section of a preferred form of peristaltic type pump of the present invention;

FIGURE 3 is an exploded isometric view of the component parts of the shaft and roller section of the pump of FIGURE 2;

FIGURE 4 is a side elevation of FIGURE 2 with a partial cross section taken along line 44 of FIGURE 2; and

FIGURE 5 is a magnified view of a portion of FIG- URE 2.

Detailed description of the invention As shown in FIGURE 1, the peristaltic type pump 10 comprises a base plate 12 formed with a recess defined by a cylindrical surface 14. Surface 14 is perpendicular to the outer surface 16 of base plate 12. An elastically deformable tube 18 having a central passage 20 passes through tubular passages 22 in base plate 12 and along the surface 14. A plurality of primary rollers 26 are positioned in equally spaced relation around shaft 24 and are carried by arms 28 which extend radially from said shaft. The primary rollers 26 are rotatably spindled to arms 28 by means of roller axles 30 which pass through rollers 26 and are attached to arms 28. Primary rollers 26 are located adjacent to surface 14 so that the portions oftube 18 between rollers 26 and surface 14 are compressed as shown at locations 34 so as to completely close central passage 20 in tube 18. Shaft 24 has a driven connection to a rotary motor (not shown). When the motor is energized and shaft 24 turns, primary rollers 26 move along tube 18 and produce a peristaltic type pumping activity along the tube 18. Any liquid that is in tube 18 is trapped between a pair of adjacent primary rollers 26 and is moved along the tube. If there is no liquid in the tube, the movement of the depressed portions of tube will create sufficient pumping vacuum to draw liquid into the tube from a connected liquid reservoir (not shown) so that it can be pumped along the tube. In order to prevent gross movement of tube 18 through the pump base 12, a retaining shoulder 32 is attached to tube 18 near an extrance to a passage 22. Retaining shoulder 32 has an outer diameter greater than the diameter of the adjacent passage 22 and will prevent movement of tube 18 into said passage. When the shaft 24 is rotating in a clockwise direction, as viewed from above in FIGURE 1, retaining shoulder 32 should preferably be located on the tube 18 at the left-hand passage 22. When the shaft 24 is rotating in a counterclockwise direction, retaining shoulder 32 should preferably be located on the tube 18 at the right-hand passage 22.

The above description of the apparatus of FIGURE 1 thus for relates to features which are common with prior art peristaltic type pumps. The pumping capacity of such pumps is a fixed value and relates directly to the available volume of the central passage 20 in tube 18. When the shaft 24 is rotating at a constant speed, there is no way to make adjustments to the pumping volume other than by substituting a tube 18 of different size central passage 20. No adjustments can be made to the positions of primary rollers 26 since they must always depress tube 18 to completely close central passage 20 or the pump will not operate properly.

In the apparatus of the present invention shown in FIGURE 1 secondary rollers 36 are positioned around shaft 24 so that each secondary roller 36 is located between two adjacent primary rollers 26. Secondary roller arms 38 are attached to rotatable shaft 24 intermediate the arms 28 and each arm 38 contains a longitudinal slot 40 near the outer end 42 thereof. Secondary rollers 36 are rotatably attached to the arms 38 in the following manner. An axle 44 passes through each secondary roller 36 and extends up through slot 40 in the associated arm 38. Suitable clamping means 46, including, for example a threaded nut, is provided on axle 44 and supports said axle, as well as secondary roller 36, at any desired position along the longitudinal slot 40. Loosening of clamping means 46 permits the secondary rollers 36 to be moved to any selected position along the slot 40, thereby providing an adjustment of the liquid volume which can be delivered by the pump. It is understood, of course, that in order for secondary rollers 36 to have any effect on the pumping volume, such rollers must depress tube 18 somewhat. It is the variation in depression that controls the pumping volume. As shown in FIGURE 1, the secondary rollers must be moved toward ends 42 in order to affect pumping volume.

While the pump shown in FIGURE 1 has three primary rollers and three secondary rollers, it should be understood that a different number of rollers can also be employed within the scope of the invention. There must be at least two primary rollers for adequate pumping action and there must be at least one secondary roller located between each pair of adjacent primary rollers.

A preferred form of the pump is shown in FIGURES 2, 3 and 4. The pump base 12 is in the form of an arm attached to a parallel shoulder 48 for pivotal movement about a screw 50. The base arm is provided with a curved surface 14 which forms at least a portion of a cylinder. An elastic tube 18 can be positioned along the curved surface 14, and primary rollers 26 and secondary rollers 36 are positioned so as to cooperate with the tube 18 and surface 14 in a manner similar to that described above for the corresponding parts of the apparatus of FIGURE 1. Primary rollers 26 and secondary rollers 36 are supported and operated, however, in a substantially different manner shown in detail in FIGURE 3 and which will now be described.

A circular support member 52 is coaxially fixed to drive shaft 24 which, in turn, has a driven connection to a rotary motor, shown as 92 in FIGURE 4, and is coaxial with surface 14 when the base arm 12 is in the operative position. Support member 52 has an upper surface 54 and a lower surface 56. A plurality of equiangularly spaced primary roller axles 30, preferably four in number, are fixedly attached to the support member 52 at equal distances from the axis thereof and depend in a perpendicular fashion from the lower surface 56. A plurality of secondary roller slots 58, preferably four in number, are formed in the upper surface 54 and extend inwardly from the periphery thereof along radii spaced equally from primary roller axles 30. Each of the slots 58 has a U-shaped vertical wall surface 60 and a flat base surface 62. The base surface 62 is disposed in a horizontal plane located approximately half way between the horizontal planes of upper surface 54 and lower surface 56. The support mem- 4 ber 52 is formed with a secondary roller axle slot 40 which extends radially inwardly from the periphery of each of the slots 58 and centrally of each of said slots. The slots 40 extend from base surface 62 to lower surface 56.

A circular secondary roller axle support 64 is coaxially fixed on each of four secondary roller axles 44, said supports being respectively positioned in the secondary roller slots 58 such that the lower ends 66 of the axles 44 pass through the slots 40 and extend beyond the lower surface 56 of support member 52. The upper ends 68 of secondary axles 44 extend above the upper surface 54 of sup port member 52, and the circular axle supports 64 rest on base surfaces 62 of secondary roller slots 58. Primary rollers 26 are rotatably mounted on the primary roller axles 30 which extend below lower surface 56 of support member 52, and secondary rollers 36 are rotatably mounted on the portions 66 of secondary roller axles 44 which extend below lower surface 56 of the support member 52.

A circular control member 69 comprises a circular dialshaped housing and an integral circular transverse wall or plate member 70. The member 70 is formed with a central circular opening 72 having a diameter somewhat larger than that of the drive shaft 24, and it is also formed with a plurality, preferably four, equally spaced, spirally arranged and similarly oriented arcuate slots 74 shown most clearly in FIGURE 3. Each of the arcuate slots 74 is arranged so that its inner end 76 is positioned about midway between the opening 72 and the periphery of member 70 and its outer end 78 is positioned near the periphery of member 7 0.

The member 70 may be suitably attached to the housing 80 at its periphery by any suitable technique, such as adhesives, fusion and the like. Alternatively and preferably the control member 69 may be of a unitary construction with the slots 74 molded or machined into a wall member portion 70 of housing 80. As shown in FIGURE 4, the wall member 70 overlies the upper surface of the support member 52 so that the drive shaft 24 passes coaxially through the opening 72 therein.

The housing member 80 has a cylindrical peripheral wall or skirt 81 which is preferably formed with external ribs 82. The upper edge of skirt 81 is joined to a frusto-conical wall 83 which, in turn, joins an inturned frusto-conical wall 84. The inner end of the frusto-conical wall 84 terminates in a vertically directed surface 85 which defines an opening 86 somewhat larger than the shaft 24 and through which said shaft extends.

The control member 69 is rotatably adjustably attached to the shaft 24 by means of a suitable snap-washer 87 removably positioned in a circumferential groove 91 formed in shaft 24. The groove 91 is positioned so that the washer 87 is located above surface 85 and exerts frictional pressure against wall 84, pressing the wall 70 axially against the support member 52.

An indicator member 88 having a circular planar head portion 89 is provided with a coaxial stem 95 which extends coaxially of the control member 69 and has a press-fit within an axial bore 97 formed in the adjacent end 93 of the shaft 24. The head portion 89 closes the open outer end of the frusto-conical wall 84 and is formed with suitable pointer means such as a diametrical groove in its outer surface. The groove 90 cooperates with indicia on the housing 80 which may take the form of equally spaced radially directed ribs 94 disposed on opposite sides of a radial primary marker rib 96, all of said ribs being formed on the outer surface of the frustoconical wall 83 of housing 80 adjacent the periphery of the circular head 89.

Upon rotation of the shaft 24, the support member 52, primary rollers 26, secondary rollers 36, control member 69 and indicator member 88 rotate therewith as a unit. The frictional contact between shaft 24 and housing 80 maintained by snap-washer 87 enables the shaft 24 and the control member 69 to rotate as a unit, This frictional contact is not so great, however, as to prevent relative movement, when desired, between control member 69 and shaft 24. The control member 69 can be manually rotated to a limited extent in either direction with respect to the shaft 24, indicator member 88 and support member 52 to thereby vary the capacity of the pump, i.e., the volume of fluid which can be pumped per revolution of the shaft 24.

More particularly, upon rotation of the control member 69 in a clockwise direction, the slots 74 exert a camming action on the secondary roller axles 44, forcing said axles and the secondary rollers 36 radially outwardly. The tube 18 is thereby compressed to a greater degree by the rollers 36, reducing the amount of fluid which can be accommodated in said tube between adjacent primary rollers 26 and thereby reducing the capacity of the pump. Conversely, counter-clockwise rotation of the control member 69 results in the slots 74 exerting a camming action which retracts the secondary rollers 36 radially inwardly to thereby reduce the compression of the tube 18 by said rollers and increase the capacity of the pump.

As shown in FIGURES 2 and 3, the secondary markers 94 on the right-hand side of the primary marker 96 are indicated and the secondary markers on the lefthand side of said primary marker are indicated thereby indicating the decrease or increase in the capacity of the pump effected by rotation of the control member 69 with respect to the shaft 24 and indicator member 88. This decrease or increase in pump capacity is relative to an intermediate capacity which is achieved when the iridicator means 90 is aligned with the primary marker 96. This apparatus thus provides a wide degree of control over the volume pumped through tube 18.

In the preferred form of the pump of the present invention, the base member 12 is mounted for movement between the operative position shown in FIGURE 2 and a retracted inoperative position (not shown) wherein no substantial compression is exerted on the tube 18 by the primary rollers 26 or secondary rollers 36. Referring to FIGURES 2 and 4, control or such movement is effected in the illustrated embodiment by a pin 98 carried by the base arm 12 and extending through a slot 100 in the shoulder plate 48. A helical spring 102 is attached at one end to the pin 98 and is anchored at its other end to a pin 104 extending from the underside of the shoulder plate 48. The spring 102 biases the base arm 12 in a clockwise direction (FIGURE 2) about the pivot screw 50 with sufiicient force to hold the pin 98 against the right-hand end of the slot 100 during operation of the pump. Abutment of the pin 98 with the right-hand end of the slot 100 defines the operative position of the base arm 12 wherein the cylindrical surface 14 thereof is substantially coaxial with the shaft 24 and control member 69, and the tube 18 is maintained under the proper compression between said surface and the rollers 26 and 36.

The compression of the tube 18 by rollers 26 and 36 can be removed by counter-clockwise pivotal movement of the base arm 12 about the pivot screw 50 against the action of the spring 102. Such movement can be effected by engagement of the pin 98 with any suitable activating means, such as activating arm 105, which is capable of moving the base arm 12 to the left to a retracted inoperative position {not shown) defined, for example, by abutment of the pin 98 with the left-hand end of the slot 100 When the base arm 12 is in the inoperative position, no fluid can be pumped even though the shaft 24 may be rotated, thus affording a means for stopping pumping action without stopping rotation of the shaft 24. This retraction to an inoperative position is primary employed, however, to relieve tube 18 of compressive stresses when the pump is not operating.

The improved pump of the present invention is also provided with means which minimizes wear on the elastic tube 18. This means takes the form of irregularities in the cylindrical surface 14 which are illustrated in FIG- URES 2 and 5 as ripples. If a smooth cylindrical surface were used for the surface 14, movement of the rollers along tube 18 would tend to cause the compressed portion of tube 18 beneath said rollers to build up some of the tube wall in front of each roller. As each roller moves over a built-up portion of tube 18, it causes undesirable sliding wear along the tube wall which tends to eventually cause a rupture of the wall. In the apparatus of the present invention, the portion of the tube wall that would normally build up in front of the roller is pushed into the valleys of the ripples and thus the sliding wear is minimized. As shown in an enlarged view in FIGURE 5, the ripples have peaks 106 and valleys 108. The radius of curvature of the valleys 108 is preferably less than the radius of the rollers 26 or 36. These rollers are both of the same size. This distance between adjacent peaks 106 is preferably less than the diameter of the rollers 26 or 36.

In summary, this relates to a peristaltic type pump having adjustable pumping capacity at constant pump speed and reduced wear on the pump tube.

What is claimed is:

1. In a peristaltic type pump having a base, an elastically deformable tube overlying said base, and at least one pair of primary rollers mounted for movement in spaced relation along said tube in a manner to compress said tube between said rollers and base and close off the central passage of said tube at the points of compression thereof by said rollers, the improvement which comprises at least one secondary roller disposed between each pair of primary rollers and mounted for movement along said tube with said primary rollers, the mounting for said secondary rollers including means for 'adjustably positioning said secondary rollers with respect to said tube and base to afford selective compression of said tube thereby throughout a range of values and thereby afford selective adjustment of the capacity of the pump.

2. A peristaltic type pump according to claim 1 wherein the base is provided with a generally cylindrical surface, and the primary and secondary rollers are rotatably attached in radially spaced relation to and positioned around a rotatable drive shaft located coaxially along the axis of said cylindrical surface.

3. A peristaltic type pump according to claim 1 wherein the surface of the base contacted by said tube is formed with irregularities.

4. A peristaltic type pump according to claim 1 wherein the mounting for said secondary rollers affords simultaneous adjustment of the position of said secondary rollers in a radial direction with respect to said cylindrical surface.

5. A peristaltic type pump according to claim 1 wherein the primary and secondary rollers are rotatably attached in radially spaced relation to and positioned around a rotatable drive shaft, a portion of the base forms an arcuate surface which supports a portion of the elastically deformable tube along a corresponding arcualte path having an axis of curvature which is coaxial with the rotatable drive shaft, a cam member having a plurality of eccentric slots is mounted normal to the drive shaft and is capable of rotational movement with respect to the drive shaft, the secondary rollers are rotatably mounted on axles which in turn engage the eccentric slots of the cam member, and the secondary rollers are capable of being simultaneously adjusted in a radial direction with respect to said base arcuate surface by rotational movement of the cam member with respect to the drive shaft.

6. A peristaltic type pump according to claim 5 wherein a rotatable drive member is attached to the drive shaft and is parallel to the cam member, the drive member having a plurality of fixed primary axles in radially spaced relation to and positioned around the drive shaft, said axles being parallel to the axis of the drive shaft, the

primary rollers are rotatably attached to the primary axles, a plurality of radial slots extend completely through the drive member, each of the radial slots being positioned between an adjacent pair of the fixed axles, a plurality of movable secondary axles are positioned in the radial slots and are parallel to the fixed axles, and the secondary rollers are rotatably attached to the secondary axles, rotational movement of the cam member with respect to the drive shaft will thus cause the secondary axles to move along the radial slots in the drive member and thus adjust the secondary rollers in a radial direction with respect to the base arcuate surface.

7. A peristaltic type pump according to claim 6 wherein a. circular control member having peripheral ribs and 1 which is capable of rotational movement with respect to the drive shaft is attached to the cam member.

References Cited UNITED STATES PATENTS 315,667 4/1885 Serdinko 103-149 328,472 10/1885 Faller 230-l68 1,703,361 2/1929 Pohl 103--149 3,011,684 12/1961 Corneil 103-149 0 3,289,232 12/ 1966 Beach -Q. 103-149 3,353,491 11/1967 Bastian 103149 DONLEY J. STOCKING, Primary Examiner.

5 WILBUR J. GOODLIN, Assistant Examiner. 

